What’s the situation of marine turtles today?
Marine turtles have been on earth for more than 100 million years. Since the start of industrialization around 200 years ago, it is estimated that total population sizes have decreased by ⅔, with some differences in the actual percentages depending on the species. Green sea turtle numbers have fallen by around 90 percent while Leatherback Turtles have lost 40 percent of their population. 6 out of the 7 species of marine turtles are listed as "critically endangered" or "endangered" by the International Union for the Conservation of Nature (IUCN).
Marine turtles play an important role in keeping balanced ecosystems, serving as both predators and prey. Marine turtles are also important in maintaining the health of seagrass beds and coral reefs by grazing on seagrass and sponges. This helps to maintain the structure of the seagrass beds and coral reefs which provide important habitat for a wide variety of marine organisms.
The main reasons for the decrease in marine turtle population sizes are the fishing industry that is killing ten thousands of marine turtles every year as bycatch, the destruction and degradation of nesting and feeding habitats such as beaches and coral reefs, for instance through coastal development and pollution, illegal trade of turtle meat, shells and eggs, plastic debris in the ocean that marine turtles ingest or become entangled in, and climate change that mostly plays a role by altering the temperature of sand on beaches where marine turtles nest, which can affect the sex of hatchlings. The combination of all these factors has led to significant declines in marine turtle populations worldwide.
What are good measures to conserve marine turtles?
Conservation of an animal species refers to the protection, management, and restoration of wild populations of that species in order to ensure the survival of the species and prevent extinction. To support their survival, we have to make changes to all the factors mentioned above that contribute to the decline in the population size of marine turtles.
As a volunteer at our Mother Nature Marine Turtle and Coastal Conservation program in Zanzibar, which activities will you do that contribute to the conservation of marine turtles?
Egg relocation and release of hatchlings
You will help to spot marine turtle nests on the beach, relocate them to a protected environment, manage the protected environment and once the turtles hatch, release them to the ocean.
This activity is important, because if the nests remain on the beach, there is a high risk that they are illegally collected by local fishermen for human consumption, which will reduce the number of potential hatchlings. If we want to increase the number of marine turtles, we need to make sure there are as many hatchlings as possible. In the ocean, only one out of 1000 hatchlings will after 15-25 years reach sexual maturity and might reproduce, which is essential for the survival of the species.
Baby turtles should be released into the ocean immediately after they hatch as they develop important orientation and survival skills at a very young age. To lay eggs, female marine turtles return to beaches in the area where they were born. If baby turtles are kept in captivity and released later, scientists have evidence that they will never develop the orientation sense needed to return those beaches and nest.
Coral reef monitoring and coral farming
Once per week we are monitoring a coral reef by snorkelling. Volunteers with a PADI Open Water Diver license can also join our coral farming activities.
This activity is important for marine turtle conservation as marine turtles, particularly those in the juvenile and adolescent stages, rely on healthy coral reefs as a source of food, place to rest and as shelter.
Activities related to pollution
As a volunteer, you will join clean-ups of beaches and villages, you will join recycling and upcycling activities and you will teach about pollution at local schools.
This is contributing to marine turtle conservation, because trash from the coast might eventually be washed into the ocean.
In the ocean, marine turtles are often found to mistake plastic debris for food, e.g. they swallow plastic bags that they might take for jellyfish. When marine turtles consume plastic, it can block their digestive tracts and cause malnutrition or death.
Marine turtles also can become entangled in plastic debris, such as abandoned fishing nets and ropes or six-pack rings, which can restrict their movement and cause injury or death.
Furthermore, plastic debris that accumulates on beaches can make it difficult for turtles to nest and lay their eggs, which can impact their reproductive success.
Promotion of permaculture and sustainable lifestyle
Twice per week you will join activities related to permaculture farming and sustainable living, e.g. making biodegradable soap. We also have various lectures on Climate Change that you will join as part of our “Climate Monday” sessions.
How is this related to marine turtle conservation?
Permaculture is a sustainable approach to farming and land use that is not making use of chemical pesticides and fertilizers.
When pesticides and fertilizers that are widely used in industrial farming enter the ocean, they can be ingested by marine turtles and other marine life. Pesticides can cause a variety of negative health effects in marine turtles, including neurological damage, immune system suppression, and cancer.
Fertilizers can also stimulate the growth of harmful algal blooms in the water, which can produce toxins that can be harmful to marine life including sea turtles. This lethal process is known as eutrophication.
In addition, pesticides and fertilizers can have indirect impacts on marine turtles by affecting the food chain. For example, if pesticides and fertilizers kill off certain types of plankton or other small marine organisms, this can have cascading effects on the rest of the marine ecosystem, including on marine turtles and other species in the food chain that rely on these organisms for food.
Industrial farming is also a main driver of climate change, with the main factors being the release of the greenhouse gas methane by large-scale livestock keeping and soil degradation through the use of chemical pesticides and fertilizers, which reduce the soil's ability to sequester carbon.
Climate change is strongly affecting marine turtles in the following ways:
Many species of marine turtles have temperature-dependent sex determination, meaning that the sex of the hatchlings is determined by the temperature of the nest. Climate change, resulting in higher nest temperatures can lead to a higher proportion of females, which can lead to an imbalance in the sex ratio of the population. This can have negative impacts on the population's ability to reproduce and maintain a stable population size. Rising temperatures can also lead to a higher incidence of nest failures.
Climate change also affects ocean currents. Changes in the patterns and strength of ocean currents can disrupt the migratory patterns of marine turtles, making it more difficult for them to find suitable nesting and feeding sites.
Rising sea levels and increased storms and flooding associated with climate change can lead to the loss and degradation of nesting beaches.
Changes in ocean temperature and pH associated with climate change can alter the distribution and abundance of marine turtles' prey species, potentially affecting their ability to find food and survive. It also results in the degradation of coral reefs that particularly juvenile and adolescent marine turtles need for food and as a shelter.
Environmental Education
As a participant in our program, you will take part in our "Ocean Mondays" and "Climate Mondays," which provide you with background knowledge needed to understand the various factors related to the conservation of marine turtles and oceans.
You can then pass on these topics as part of the environmental education we organize to local school children and tourists. Tourists should, for example, refrain from consuming certain fish species and seafood that have not been sustainably caught.
Industrial fishing is a major reason for the decline in the sea turtle population. The fishing industry uses unsustainable fishing methods such as trawls, longlines, driftnets, gillnets, pots, and traps that are responsible for the death of marine creatures by incidental capture (bycatch) or entanglement.
About 40% of all animals caught in fisheries are bycatch. Marine mammals like dolphins, marine turtles, seabirds, and many fish species are caught and thrown dead back into the ocean because they are not of interest for human consumption or their sale is not financially attractive. For injured animals released alive, their fate after release is unknown. Longlines, containing thousands of baited hooks on lines that can be tens of kilometers long, entangle many animals not intended to be caught. Marine turtles, especially green turtles, loggerhead, olive ridley, and leatherback turtles, are attracted to the bait and get snagged on the hooks or entangled in the lines, leading to drowning.
To support marine turtle conservation, it is important that tourists and the general population are aware of this situation and change their behavior by rejecting industrially caught fish. You can support this, for example, by posting about it on social media and other channels. In our Mother Nature Camps, we do not serve fish that has been caught in unsustainable ways or species that are overfished.
Which types of activities are not considered best practices related to marine turtle conservation?
There are many projects all around the world that claim to do marine turtle conservation, but are in fact rather counterproductive.
You should in general be very wary about any project keeping marine turtles in captivity (maybe with the exception of short-time veterinary treatment).
As mentioned before, it is now general scientific consensus that hatchlings should not be kept in captivity, even for short times, as they will fail to develop their orientation and other critical survival skills, which will prevent them from reaching the age of maturity and the ability to return to their nesting beaching.
Catching marine turtles from the ocean and keeping them in pools, ponds, aquariums etc. to “protect” them from being killed for their meat or shells is also not contributing to conservation of the species. To make sure the species survives, the number of marine turtles needs to increase. To achieve this, the turtles need to reproduce. Marine turtles in captivity usually don't reproduce.
Reasons why marine turtles in captivity don't reproduce:
Almost all turtles kept in captivity are females. Only female turtles swim close to the coasts in order to nest and are therefore caught by fishermen. Without a male, they can obviously not mate.
To nest, turtles need to swim to beaches near the area where they were born. When in captivity, they cannot reach these beaches.
If female turtles are caught while carrying fertilized eggs inside them and they cannot find a suitable beach for nesting, they will dispose of the eggs in the water. Those eggs are all dead then.
Even if male and female turtles are kept together in captivity, there is very little breeding success as water quality, temperature, lighting, stress, health problems and social dynamics are different from those in the wild, interfering with their ability to breed.
Activities offered to tourists at marine turtle attractions keeping marine turtles in captivity such as swimming with and touching marine turtles are a major reason for stress and health problems of marine turtles, so you should definitely stay away from projects offering such types of activities.
When choosing a marine turtle conservation project to volunteer for, please make sure that it supports activities that are really beneficial to the conservation of marine turtles, as summarized in this article. This might mean you will not be in close contact with marine turtles because they are in the ocean where they belong to and not in a pool or pond. Educating the population, cleaning beaches, relocating eggs, restoring natural habitats etc. will definitely contribute much more to marine turtle conservation than holding or cuddling turtles.
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